1. Field of the Invention
The present invention relates to a carbon nanotube-based device and a method for making such a carbon nanotube-based device. The application relates a contemporaneously filed application, titled “CARBON NANOTUBE ARRAY AND METHOD FOR MAKING SAME” and having the same applicants and the same assignee with the instant invention.
2. Description of Related Art
Carbon nanotubes are very small tube-shaped structures having the composition of a graphite sheet rolled into a tube. Carbon nanotubes produced by arc discharge between graphite rods were first discovered and reported in an article by Sumio Iijima entitled “Helical Microtubules of Graphitic Carbon” (Nature, Vol. 354, Nov. 7, 1991, pp. 56–58). Carbon nanotubes have electrical conductance relate to their structure, and are chemically stable, and have very small diameters (less than 100 nanometers) and large aspect ratios (length/diameter). Due to these and other properties, it has been suggested that carbon nanotubes can play an important role in fields such as microscopic electronics, materials science, biology and chemistry.
Although carbon nanotubes promise to have a wide range of applications, better control is desirably needed over the building and organization of nanotubes-based architectures with controlled orientation. Chemical vapor deposition has been used to align nanotubes vertically on catalyst-printed substrates. For instance, a method for controlling the growth of aligned nanotubes in several directions on a substrate at once in a single process was reported in an article by B. Q. Wei et al. entitled “organized assembly of carbon nanotubes” (in Nature 416, 495–496, Apr. 4, 2002).
Another method for controlling the growth of carbon nanotubes by means of electric fields was reported in an article by Yuegang Zhang et al. entitled “Electric-field-directed growth of aligned single-walled carbon nanotubes” (Applied Physics Letters, Vol. 79, 19, Nov. 5, 2001).
However, carbon nanotubes of all the carbon nanotube based structures obtained by the above-mentioned methods are aligned along a linear direction, and/or extend perpendicularly from the substrates. Furthermore, the method of using an external field to control a growth direction of the carbon nanotubes is difficult to achieve localized complicated structures with multiple orientations of the carbon nanotubes. Therefore, diversified design of carbon nanotube-based devices is strictly limited.